Antsirabe in central Madagascar, suggesting a broad former distribution. Its range is not known to overlap that of H. antimena, which has undergone a dramatic reduction during the Holocene. A bone from Andrahomana has been radiocarbon dated to about 4440 BP and another to 1536 BP. Although almost nothing is known of the ecology of H. australis, Goodman and Rakotondravony presumed that it was similar to its living relative in living in burrows in areas with loose soils. H. australis shows relatively high content of carbon-13 isotope, likely because it ate some plants which were enriched in carbon-13 through C4 carbon fixation and crassulacean acid metabolism; both of these photosynthesis-related processes occur most frequently in plants adapted to dry environments. Hypogeomys australis is one of only three extinct rodents known from Madagascar (the others are Brachytarsomys mahajambaensis and Nesomys narindaensis from northwestern Madagascar). In general, few small animals became extinct on Madagascar, except for these rodents, two species of Plesiorycteropus, and the shrew tenrec Microgale macpheei; in contrast, large animals such as subfossil lemurs, the carnivore Cryptoprocta spelea, Malagasy hippopotamuses, Dipsochelys tortoises, and Aepyornis and Mullerornis birds all became extinct around the time that humans arrived. References Literature cited Burney, D.A., Burney, L.P., Godfrey, L.R., Jungers, W.L., Goodman, S.M., Wright, H.T. and Jull, A.J.T. 2004. A chronology for late prehistoric Madagascar (subscription required). Journal of Human Evolution 47:25–63. Crowley, B.E., Godfrey, L.R. and Irwin, M.T. 2010. A glance to the past: subfossils, stable isotopes, seed dispersal, and lemur species loss in Southern Madagascar (subscription required). American Journal of Primatology 71:1–13. Goodman, S.M. and Rakotondravony, D. 1996. The Holocene distribution of Hypogeomys (Rodentia: Muridae: Nesomyinae) on Madagascar. Biogéographie de Madagascar 1996:283–293. Grandidier, G. 1903. Description de lHypogeomys australis, nouvelle espèce de Rongeur sub-fossile de Madagascar. Bulletin du Muséum national d'histoire naturelle 9:13–15 (in French). MacPhee, R.D.E. 1994. Morphology, adaptations, and relationships of Plesiorycteropus, and a diagnosis of a new order of eutherian mammals. Bulletin of the American Museum of Natural History 220:1–214. Mein, P., Sénégas, F., Gommery, D., Ramanivoso, B., Randrianantenaina, H. and Kerloc'h, P. 2010. Nouvelles espèces subfossiles de rongeurs du Nord-Ouest de Madagascar (subscription required). Comptes Rendus Palevol 9(3):101–112 (in French, with abridged English version). Musser, G.G. and Carleton, M.D. 2005. Superfamily Muroidea. Pp. 894–1531 in Wilson, D.E. and Reeder, D.M. (eds.). Mammal Species of the World: a taxonomic and geographic reference. 3rd ed. Baltimore: The Johns Hopkins University